/Engine/Source/Runtime/Engine/Public/SaveGameSystem.h
Indicates that an async savegame exists check has completed. SlotName, PlatformUserId, save exists result. Should always be called from the gamethread.
typedef [TFunction](API\Runtime\Core\GenericPlatform\TFunction)< void(const [FString](API\Runtime\Core\Containers\FString) &, [FPlatformUserId](API\Runtime\Core\Misc\FPlatformUserId), [ISaveGameSystem::ESaveExistsResult](API\Runtime\Engine\ISaveGameSystem\ESaveExistsResult))> FSaveGameAsyncExistsCallback